"DIMMs do not have backwards compatibility with SIMMs, therefore it is not possible to slowly simply upgrade the memory modules. Moving from SIMMs to DIMMs required a replacement of the motherboard which could sometimes mean the replacement of the processor"

SIMM's are single line, DIMMS are dual line. If your PC is running, it's operating on a single Memory module, and will blue screen when it tries to use whatever is in the other slot. I'm amazed it gets past the POST at all. It is not wise to use both at once. At all.

The two types of memory have pin connections on both sides, but on a SIMM the opposite side is redundant and does nothing. SIMMs died out nearly two decades ago, as producing DIMMs allowed for more capacity.

So now that we are on the same page, what in Hades is the question here? You seem to imply that you can put SIMMs and DIMMs together, and have them work. This is impossible, as no hardware offered the ability to physically install both types of RAM at the same time. They have fundamentally different pin configurations, and therefore would not actually fit.

You use the term "card." Is that a memory module? What exactly are you working with? Are you trying to install Windows 7 on a system that is 20 years old, and getting errors because you don't have enough RAM?

I would suggest two things here. Do a little research, and make sure we are all on the same page with terminology. It makes trouble shooting easier. Frame your problem with some extra information. Nobody can offer you help if you can't tell us what is going on. Address these two issues and we can help, otherwise we're not really capable of helping because we don't know what the problem actually is.

I don't see how it could possibly work, apart from the format already mentioned, most dimms are 168 or 184 pin and most simms are 30 or 72 pin, now unless you can find a motherboard that supports both, which you can't I think someone is either bored or smokin da stuff! .... thread closed for sanity's sake (mine )